The goal of this application is to provide the candidate with mentored, in-depth research training to become an independent investigator. To achieve this goal, the proposal includes a structured career plan for the candidate's development as a physician-scientist and a research project that focuses on the mechanisms of airway inflammation in alpha-1 antitrypsin deficiency (AATD). The candidate is a new faculty member with strong commitment to AATD related-research. The sponsor and co-sponsor are established investigators in airway biology and the collaborators are established investigators in the field of AATD research. The overall goal of the research project is to understand the pathogenesis of airway inflammation and chronic bronchitis in AATD, a condition significantly associated with the worst quality of life and more severe airway disease exacerbations in these subjects. Our preliminary studies show that serous cells in the normal airway epithelium and airway submucosal glands (SMG) secrete significant amounts of alpha-1 antitrypsin (AAT). The central hypothesis of the research project is that airway inflammation in AATD is due to a) the loss of AAT activity (from local and systemic origin), b) the extracellular presence of modified AAT molecules that act as chemoattractants in the airway lumen, and c) dysfunction of serous cells, a consequence of accumulating mutant AAT in the endbplasmic reticulum (ER). The aims will test these mechanisms using human airway epithelial cells cultured at the air-liquid interface (ALI) and SMG cell cultures from normal subjects as well as bronchial cells from patients with AATD. Specific Aim 1 will test if loss of AAT activity increases the susceptibility of normal airway epithelial cells to elastase-induced mucin and IL-8 production by testing the effects of adding to ALI cultures basolaterally ("systemic") AAT and suppressing endogenous (local) AAT in SMG cells with the use of siRNA. Specific Aim 2 will investigate the pro-inflammatory effects of AAT polymers and C-36 peptide (AAT degradation product) addition to the apical side of normal ALI cultures on neutrophil migration (and activation) across the airway epithelium by measuring neutrophil transepithelial migration and subsequent epithelial induction of mucin and IL-8 production. In addition, in this Aim we will assess if AAT polymers and C-36 peptides are present in inflamed airways. Specific Aim 3 will test if intracellular accumulation of mutant AAT in airway serous cells leads to ER stress, induction of IL-8, release of AAT polymers and serous cell apoptosis with loss of serous cell function by using Calu-3 cells transfected with mutant AAT and epithelial cells obtained bronchoscopically from AATD patients. Relevance: Collectively, these studies will help improve our understanding of the physiologic mechanisms of airway inflammation in AATD and provide insight on the role of local airway AAT production, while providing the applicant with the appropriate expertise to begin a productive career as an independent investigator.